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PubMed2005

Amiodarone and the thyroid.

Among the drugs affecting the thyroid gland, no drug has puzzled, and at the same time fascinated, endocrinologists more than amiodarone. Amiodarone is a potent class III anti-arrhythmic drug that also possesses beta-blocking properties. It is very rich in iodine, with a 100-mg tablet containing an amount of iodine that is 250 times the recommended daily iodine requirement. Amiodarone produces characteristic alterations in thyroid function tests in euthyroid patients. Understanding these alterations is crucial in avoiding unnecessary investigations and treatment. Amiodarone-induced thyroid dysfunction occurs because of both its iodine content and the direct toxic effects of the compound on thyroid parenchyma. Amiodarone-induced hyperthyroidism is more common in iodine-deficient regions of the world, whereas amiodarone-induced hypothyroidism is usually seen in iodine-sufficient areas. In contrast to amiodarone-induced hypothyroidism, amiodarone-induced thyrotoxicosis is a difficult condition to diagnose and treat. In this review, we discuss the alterations in thyroid function tests seen in euthyroid subjects, the epidemiology and mechanism of amiodarone-induced thyroid dysfunction, treatment options available, and the consequences of amiodarone use in pregnancy and lactation; and finally, we propose a follow-up strategy in patients taking amiodarone.

Amiodarone↗
PubMed2003

Management of hypo- and hyperthyroidism during pregnancy.

Pregnancy has profound effects on the regulation of thyroid function, and on thyroidal functional disorders, that need to be recognized, carefully assessed and correctly managed. Relative hypothyroxinemia and goitrogenesis may occur in healthy women who reside in areas with restricted iodine intake, strongly suggesting that pregnancy constitutes a stimulatory challenge for the thyroid. Overt thyroid dysfunction occurs in 1-2% of pregnant women, but mild forms of dysfunction (both hyper- and hypothyroidism) are probably more prevalent and frequently remain unrecognized. Alterations of maternal thyroid function have important implications for fetal and neonatal development. In recent years, particular attention has been drawn to the potential risks for the developing fetus due to maternal hypothyroxinemia during early gestation. Concerning hyperthyroidism, the two main causes of thyrotoxicosis in the pregnant state are Graves' disease and gestational transient thyrotoxicosis (GTT). The natural history of Graves' disease is altered during pregnancy, with a tendency for exacerbation during the first trimester, and amelioration during the second and third trimesters. The natural history of the disorder must be considered when treating patients, since antithyroid drugs cross the placenta and can directly affect fetal thyroid function. Algorithms to routinely screen pregnant women for thyroid dysfunction have been proposed in recent years, but these have not yet been implemented systematically, nor have they been the subject of cost-effectiveness analyses.

Female↗
PubMed1998

Plasma cholesteryl ester transfer protein activity in hyper- and hypothyroidism.

Thyroid dysfunction is associated with multiple changes in lipoprotein metabolism, and we have determined the effects of thyroid dysfunction on plasma cholesteryl ester transfer protein (CETP) activity. CETP is a plasma protein that mediates the exchange of cholesteryl ester and triglyceride between plasma lipoproteins and plays an important role in high-density lipoprotein metabolism and in the reverse cholesterol transport pathway. Plasma CETP activity was assayed in 18 hyperthyroid and in 17 hypothyroid patients, before and after treatment, by measuring the transfer of cholesteryl esters from exogenous radiolabeled high-density lipoprotein to apolipoprotein B-containing lipoproteins. Plasma CETP activity was increased in hyperthyroid patients, compared with their matched controls (22.11 +/- 8.92% transferred/5 microL.4 h vs. 16.75 +/- 6.48, P < 0.05), whereas in hypothyroid patients, plasma CETP activity was decreased (11.14 +/- 4.84% transferred/5 microL.4 h vs. 17.26 +/- 7.13, P < 0.01). Plasma CETP activity decreased after treatment of thyrotoxicosis, although a significant change was observed, mainly in the severely thyrotoxic patients with free T4 > 100 pmol/L (n = 11, 25.61 +/- 8.12% transferred/5 microL.4 h vs. 21.71 +/- 7.84, P < 0.05). In the hypothyroid patients, there was a significant increase in plasma CETP activity after thyroxine replacement (11.14 +/- 4.84% transferred/5 microL.4 h vs. 15.46 +/- 6.71, P < 0.01). There was a strong positive correlation between log(free T4) and plasma CETP activity (r = 0.51, P < 0.001). In summary, both hyper- and hypothyroidism are associated with significant changes in plasma CETP activity, and these changes are corrected when the patients have been rendered euthyroid.

Adult↗
PubMed1992

Risk factors for developmental disorders in infants born to women with Graves disease.

OBJECTIVE: To identify risk factors for disorders of fetal growth and thyroid function in the presence of maternal Graves disease. METHODS: Two hundred thirty pregnancies in gravidas with Graves disease were analyzed. Maternal thyroid status was evaluated by serum free thyroxine (T4) or free T4 index, TSH, and TSH-receptor antibody; personal history of thyrotoxicosis and total dose of antithyroid drugs during pregnancy were also noted. Neonatal thyroid function was assessed at birth and on the fifth day after birth. RESULTS: Fifteen neonates (6.5%) were small for gestational age (SGA), and this occurrence was significantly associated with thyrotoxicosis lasting for 30 weeks or more of pregnancy, TSH-receptor antibody level of 30% or more at delivery, history of Graves disease of 10 years or longer, and onset of Graves disease before 20 years of age. However, no significant correlation was found between maternal thyroid hormone level and SGA neonates. Thyroid dysfunction developed in 38 infants (16.5%), of whom only four were SGA; development of this dysfunction was significantly related to the mother's total dose of antithyroid drugs, duration of thyrotoxicosis in pregnancy, and/or TSH-receptor antibody level at delivery. CONCLUSIONS: Duration of maternal Graves disease or thyrotoxicosis, either mild chemical or overt, in pregnancy is significantly associated with SGA neonates. Neonatal thyroid dysfunction is associated with the maternal thyroid condition, especially the serum TSH-receptor antibody level.

Adult↗
PubMed1991

Effects of short and long duration hypothyroidism and hyperthyroidism on the plasma adrenocorticotropin and corticosterone responses to ovine corticotropin-releasing hormone in rats.

We report here a study of the plasma ACTH and corticosterone responses to synthetic ovine CRH (oCRH) in hypothyroid and hyperthyroid rats studied 7, 15, and 60 days after either thyroidectomy or the administration of pharmacological doses of T4. The purpose of this study was to further clarify the time-dependent effects of alterations in thyroid status on the functional integrity of the hypothalamic-pituitary-adrenal axis and to aid in the interpretation of the oCRH stimulation test in hypo- and hyperthyroid states. Our data demonstrate that hypothyroid rats have a significant reduction in the cerebrospinal fluid (CSF) levels of corticosterone and a significant decrease in adrenal weight in association with significant increases in the plasma ACTH response to oCRH. On the other hand, the corticosterone response to the ACTH released during the oCRH stimulation test was significantly reduced in hypothyroidism. With increasing duration of thyroidectomy-induced hypothyroidism, there was a progressive fall in CSF corticosterone levels, a progressive increase in the plasma ACTH response to oCRH, and a gradual normalization of the corticosterone responses to the ACTH released during oCRH stimulation. Our findings in hyperthyroid rats were generally the converse of those seen in hypothyroidism. Hence, there was a significant increase in the CSF levels of corticosterone and a significant increase in adrenal weight in association with an initial slight decrease in the ACTH response to oCRH. On the other hand, the corticosterone response to the ACTH released during oCRH stimulation was significantly increased. There was a gradual increase in the magnitude of the rise in CSF corticosterone levels with time, as well as a gradual normalization of adrenocortical responses during oCRH stimulation. The ACTH plasma clearance rates were similar in hypo-, hyper-, and euthyroid rats. Our data do not permit definitive identification of the precise locus in the hypothalamic-pituitary-adrenal axis that is principally affected by experimentally induced alterations in thyroid status. However, these data are most compatible with a subtle hypothyroid-induced centrally mediated adrenal insufficiency and a subtle hyperthyroid-induced centrally mediated hypercortisolism. These data also suggest that alterations in hypothalamic-pituitary-adrenal function in states of disturbed thyroid function become somewhat more pronounced as the duration of thyroid dysfunction increases. The fact that pituitary-adrenal responses to oCRH are consistently altered in states of thyroid dysfunction may be relevant to the clinical interpretation of oCRH stimulation tests.(ABSTRACT TRUNCATED AT 400 WORDS)

Adrenocorticotropic Hormone↗
PubMed1992

Endocrine deficit after fractionated total body irradiation.

Endocrine function was assessed in 31 children (17 boys) after fractionated total body irradiation used in the preparative regimen for bone marrow transplantation. Endocrine dysfunction was present in 25 children. Fifteen of 29 had growth hormone insufficiency 0.9-4.9 years after total body irradiation, yet only three of the 15 had received previous cranial irradiation. Five of 30 had thyroid dysfunction: two with a low thyroxine and raised thyroid stimulating hormone (TSH) concentration and three with a raised TSH and normal thyroxine concentration. Thus the incidence of thyroid dysfunction (16%) is much lower than that reported after single fraction total body irradiation (39-59%). In only two children were abnormalities of the hypothalamic-pituitary-adrenal axis demonstrated. The majority of pubertal children assessed (n = 15) showed evidence of gonadal damage. All the pubertal girls (n = 5) had ovarian failure, although there was evidence of recovery of ovarian function in one girl. All seven boys in late puberty showed evidence of damage to the germinal epithelium, and two of three in early puberty had raised follicle stimulating hormone concentrations. Despite the use of a fractionated total body irradiation regimen, endocrine morbidity is substantial and children undergoing such procedures will require long term endocrine review and management.

Adolescent↗
PubMed1989

Transient infantile hyperthyrotrophinaemia.

Sixteen cases of transient infantile hyperthyrotrophinaemia were followed up for two to seven years. Concentrations of serum triiodothyronine, thyroxine, and free thyroxine were maintained within the normal range in all cases. All but one child, who had a hearing disturbance, showed normal mental development with normal physical and skeletal maturation. Eleven children had normal concentrations of serum thyroid stimulating hormone and no signs or symptoms of thyroid dysfunction; in three children, diffuse small goitres developed and two further children showed relapse with slightly raised concentrations of thyroid stimulating hormone. It is concluded that 'transient infantile hyperthyrotrophinaemia' is a syndrome, which differs from typical transient neonatal hypothyroidism, and that careful follow up is necessary because some children show signs of mild pituitary-thyroid dysfunction in later childhood.

Child Development↗
PubMed2026

Thyroid-joint crosstalk: a systematic review and meta-analysis of thyroid autoimmunity and dysfunction in juvenile idiopathic arthritis.

BACKGROUND: Recent observational studies outlined the concomitant presence of autoimmune diseases in children with juvenile idiopathic arthritis (JIA), including endocrine autoimmunity. Despite the growing evidence of thyroid involvement in JIA, available data are heterogeneous and fragmented. We aimed to systematically review the available evidence on the prevalence of thyroid autoantibody positivity and thyroid dysfunction in patients with JIA. METHODS: PubMed/Medline, Cochrane, and Scopus databases were approached to identify studies reporting data on thyroid autoantibody positivity and dysfunction in children with JIA. RESULTS: A total of 15 studies were included in the final analysis, encompassing 19 015 children with JIA (13 225 females, 69.6%) with a weighted mean age of 8.0 years (range 1.8-21 years). The pooled prevalence estimates of antithyroid antibody positivity and thyroid dysfunction were 0.04 (95% CI: 0.03-0.05) and 0.04 (95% CI: 0.03-0.08), respectively. The risk difference for thyroid autoantibody positivity between children with JIA and controls was 0.08 (95% CI: 0.02-0.14). Possible risk factors were analyzed: the presence of family history for thyroid autoimmune disease (odds ratio - OR 3.91, 95% CI 1.86-8.25), concurrent Antinuclear Antibodies (ANA) positivity (OR 1.62, 95% CI 1.13-2.31), and older age (MD 2.10 years, 95% CI 1.32-2.89) were associated with thyroid autoantibody positivity and/or thyroid dysfunction in children with JIA. No significant difference emerged for the specific JIA form. CONCLUSION: Thyroid dysfunction may be detected in children with JIA, with a significant risk difference in comparison to healthy controls. Specific clinical characteristics, such as family history, ANA positivity, and older age at JIA onset, may suggest which patients should benefit from thyroid autoantibody screening.

Humans↗
PubMed1999

Autoimmune events during interferon beta-1b treatment for multiple sclerosis.

Autoimmune events, although rarely reported during interferon beta-1b (IFNB) treatment of relapsing-remitting (RR) multiple sclerosis (MS), may be more frequent than expected due to the many immunologic abnormalities associated with this disease. We report the prospective two-year follow-up of autoimmune events in 40 RR MS patients treated with IFNB and in 21 untreated MS controls. Thyroid and liver function and serum level of 12 autoantibodies (autoAbs) against organ- (thyroid, gastric, pancreatic) and non-organ-specific antigens were serially monitored. In contrast to control patients, autoAbs (anti-nuclear, -smooth muscle or -thyroid antigens) were detected in 13 IFNB-treated patients, and these were associated with thyroid or liver function alteration in many cases. Persistent autoimmune thyroid dysfunction occurred in three IFNB-treated patients, all of whom were women with a familial history of thyroid disease or baseline anti-thyroid autoAb positivity. For improvement of the MS relapse rate, thyroid dysfunction was adequately treated without stopping IFNB. Liver function alteration (17 IFNB-treated patients, associated with non-organ-specific autoAbs in four) was transient and did not require IFNB treatment to be stopped, with the exception of one patient who was already suffering from a drug-induced hepatopathy at baseline. During the IFNB treatment of MS, several autoimmune events may occur, indicating that thyroid and liver function and autoAbs must be carefully monitored.

Adult↗
PubMed2001

Ten-year follow-up of thyroid function in lithium patients.

The objective of this paper was to study prospectively the course of clinically relevant thyroid dysfunction in a cohort of patients on long-term lithium treatment. Patients (N = 150) who had undergone a cross-sectional evaluation of their thyroid function in 1989, when they were at different stages of lithium treatment, were followed up for the presence of thyroid autoimmunity, hypothyroidism, and goiter during a further period of lithium exposure of up to ten years. The following annual rates of newly developed thyroid dysfunction were observed: autoimmunnity (1.4%), subclinical hypothyroidism (1.7%), and goiter (2.1%). Subjects with thyroid autoimmunity had a higher chance of requiring substitution treatment with levothyroxine for subclinical hypothyroidism compared with subjects with no evidence of thyroid autoimmunity (13/32 = 41% versus 7/118 = 6%). Subjects (N = 15) who were prescribed carbamazepine in addition to lithium showed a significant decrease of TSH concentrations. In patients already being treated with lithium for several years, the overall incidence of hypothyroidism, goiter, and thyroid autoimmunity were comparable with those reported for the general population. However, lithium exposure may represent an additional risk factor for hypothyroidism in women and/or in the presence of thyroid autoimmunity.

Antimanic Agents↗
PubMed2004

Radiotherapy-induced thyroid disorders.

Despite their specific functional consequences, radiotherapy-induced thyroid abnormalities remain under-estimated and underreported. These sequelae may include primary or central hypothyroidism, thyroiditis, Graves' disease, euthyroid Graves' ophthalmopathy, benign adenomas, multinodular goitre and radiation-induced thyroid carcinoma. Primary hypothyroidism, the most common radiation-induced thyroid dysfunction, affects 20-30% of patients administered following curative radiotherapy to the neck region, with approximately half of the events occurring within the first 5 years after therapy. The relative risk of radiation-induced cancer (mainly well-differentiated tumours) is 15-53-fold higher than in non-irradiated population. The aetiology of radiation-induced thyroid injury includes vascular damage, parenchymal cell damage and auto-immune reactions. Total radiotherapy dose, irradiated volume of the thyroid gland, and the extent of prior thyroid resection are among the most important factors associated with the risk of hypothyroidism. The contribution of other treatment modalities (chemotherapy, endocrine therapy) as well as patient- and tumour-related factors is less clear. Reduction in radiation dose to the thyroid gland and hypothalamic/pituitary complex should be attempted whenever possible. New radiotherapy techniques, such as stereotactic radiosurgery, three-dimensional conformal irradiation, intensity modulated radiotherapy and proton therapy allow generally better dose distribution with lower dose to the non-target organs. The diagnostic approach to thyroid radiation injury includes baseline thyroid function assays in all patients undergoing thyroid or parasellar irradiation. Recommended follow-up procedures include at least annual evaluation with a history for symptoms of thyroid dysfunction, clinical examination, and measurement of thyroid hormones and thyrotropin. Management of overt hypothyroidism is based on hormone replacement therapy. Thyroid hormone therapy is also recommended in cases of subclinical hypothyroidism. Treatment of other radiation-induced thyroid disorders (thyroiditis, Graves' disease, thyroid cancer) is similar to that employed in spontaneously occurring conditions. Further improvements in radiotherapy techniques and progress in endocrine diagnostics and therapy may allow better prevention and management of radiation-related thyroid injury.

Adenoma↗
PubMed1988

Screening for thyroid disease in the elderly. Serum concentrations of thyrotropin and 3,5,3'-triiodothyronine in a representative population of 79-year-old women and men.

Thyroid function in individuals from a representative population of 79-year-olds was evaluated clinically and from measurements of serum thyrotropin (TSH) and 3,5,3'-triiodothyronine (T3). High TSH concentrations (greater than or equal to 10 mU/l) were found in 16 of 320 women (5%) and 2 of 204 men (1%). Signs and symptoms which traditionally are regarded as related to hypothyroidism were as common in subjects with high TSH concentration as in the remaining population and occurred in 10-50% of the subjects. In the 16 women with high TSH, free thyroxine (free T4) concentrations were low in 10, whereas only one subject had low thyroxine (T4) and T3 concentrations, indicating that free T4 is a more sensitive parameter for thyroid hypofunction in the elderly. Based on the T3 assay, there was no evidence for hyperthyroidism in this population. The results indicate that high TSH concentrations are common in elderly women, less common in men. The results show that classical symptoms of thyroid dysfunction are quite common in 79-year-olds, but do not correlate with biochemical indicators of thyroid dysfunction, indicating that defining "clinically euthyroid" in an elderly may be almost impossible.

Aged↗
PubMed2006

[Drugs affecting thyroid--part II].

The use of several groups of medications may result in thyroid dysfunction. So far the best known medication is amiodarone. The role of other medications and diagnostic agents in causing thyroid dysfunction is quite often forgotten. We presented medications and diagnostic agents commonly used in medical day-to-day practice. We described other than amiodarone iodinated agents and quoted recently published European guidelines in using iodinate contrast agents. We focused on lithium and psychiatric drugs and mechanism of their toxic impact on thyroid gland. These agents are important as they are applied for years (including children). At the end the impact of cytokines on thyroid gland was discussed, medications ever more widely applied in anti-viral and anti-neoplastic therapy.

Amiodarone↗
PubMed1994

The iodide perchlorate discharge test in women with previous post-partum thyroiditis: relationship to sonographic appearance and thyroid function.

BACKGROUND: Post-partum thyroid disease occurs in 50% of anti-thyroid peroxidase (TPO) antibody positive women (detected at 16 weeks' gestation) and is characterized by a transient episode of hyper, hypo or hyper-hypothyroidism. In approximately 20% of these women the hypothyroidism is permanent. However, the extent of long-term thyroid dysfunction, possibly mediated by immune attack, in those anti-TPO Ab + ve women who have had only transient or no thyroid dysfunction during the postpartum period is not clear. OBJECTIVE: We have therefore studied the frequency of iodide organification defects by iodide perchlorate discharge testing, and of thyroid morphological abnormalities by ultrasound scanning in euthyroid women following their episode of post-partum thyroiditis (PPT). DESIGN: The study group comprised 17 women with previous PPT (PPT + ve) and 12 women who had positive anti-TPO antibodies during pregnancy but who did not develop PPT (PPT - ve). Women were studied 15-47 months following their episode of PPT. RESULTS: Iodide perchlorate discharge tests were positive (more than 10% discharge) in 7 (41%) PPT + ve and 5 (42%) PPT-ve subjects (P = NS). Morphological abnormalities on thyroid ultrasound were detected in 7 of 14 (50%) PPT + ve and 7 of 9 (77%) PPT - ve subjects (P = NS). There was a strong association between abnormalities of iodide organification and morphology: of 11 subjects with positive iodide perchlorate discharge tests, 10 had abnormal (positive) ultrasound scans; of 12 subjects with negative iodide perchlorate discharge tests 8 had negative ultrasound scans (P = 0.013, Fisher's exact test). CONCLUSIONS: Long-term subtle defects of thyroid function and morphology are common in women with anti-TPO antibodies in pregnancy, whether or not they develop post-partum thyroiditis. The clinical significance of these findings is unclear but a continuing thyroid pathological process is suggested.

Adult↗
PubMed1990

Thyroid abnormalities in the McCune-Albright syndrome: ultrasonography and hormonal studies.

Hyperthyroidism and goiter have been reported frequently in association with the McCune-Albright syndrome (MAS). To assess the prevalence and extent of thyroid abnormalities in girls with MAS, we studied 19 patients [mean age, 6.6 +/- 1 (+/- SE) yr; mean bone age, 9.5 +/- 1 yr] and 18 normal control girls (mean age, 10.3 +/- 0.5 yr). All patients appeared euthyroid when examined; 1 was taking antithyroid medication. Ultrasonography revealed thyroid abnormalities in 7 patients, including generalized inhomogeneity, small (2-4 mm) and large (greater than 10 mm) hypoechoic regions, and echogenic nodule-like regions. Repeat ultrasonography after intervals of 9-18 months showed enlargement of large hypoechoic regions in 2 patients. In the patients with abnormal ultrasound findings, serum TSH was uniformly low or suppressed both at baseline and after administration of 7 micrograms/kg TRH. The mean serum T3 level in this group was significantly higher than that in controls (2.9 +/- 0.2 vs. 2.3 +/- 0.1 nmol/L; P less than 0.05), whereas mean serum T4, free T4, and T4-binding globulin levels did not differ from those of controls. In the remaining 11 patients, thyroid ultrasonography was normal, and the serum levels of T3, T4, free T4, and TSH were normal. Bioassay showed no detectable thyroid-stimulating activity in the plasma of the MAS patients with suppressed TSH levels. None of the patients became overtly thyrotoxic over 3-6 yr of observation, and their serum iodothyronine levels remained stable. We conclude that thyroid dysfunction is common in girls with MAS, but that it may be clinically occult and not rapidly progressive. The thyroid dysfunction, like that of the ovaries, is associated with structural abnormalities in the gland itself, together with suppressed levels of the respective stimulating hormones.

Adolescent↗
PubMed2003

Thyroid orbitopathy.

BACKGROUND: Thyroid orbitopathy (thyroid eye disease, thyroid ophthalmopathy) is an organ specific, autoimmune disorder with the potential to cause severe functional and psychosocial effects. OBJECTIVE: This article reviews the clinical features with particular emphasis on current management. DISCUSSION: Thyroid orbitopathy is most prevalent in women aged 40-50 years and is usually associated with thyroid dysfunction. Clinical manifestations include soft tissue signs, lid retraction, lid lag, proptosis, restrictive myopathy, corneal exposure and optic neuropathy. Thyroid function tests are essential, while thyroid antibodies and imaging to demonstrate extraocular muscle enlargement may also aid diagnosis. Correction of thyroid dysfunction and supportive measures are necessary in all cases. Immunosuppression is reserved for moderate to severe active orbitopathy and rehabilitative surgery is generally used once the disease is quiescent. A good visual and cosmetic outcome requires close cooperation between the general practitioner, endocrinologist and ophthalmologist.

Female↗
PubMed1987

[Depressions resistant to tricyclic antidepressive treatment and hypothyroidism].

The relationship between thyroid disorders and depression is well known. This type of endocrine disease is mainly observed in patients with depression resistant to appropriate antidepressor therapy. Three clinical forms of this association may be distinguished: hypothyroidism in a patient with depression but without a previous psychiatric history; a relapse of depression in a manico depressive patient who has developed hypothyroidism; the finding of slight thyroid dysfunction (increased TSH response after injection of TRH) in a patient with depression. The frequency of the association of hypothyroidism and resistant depression underlines the need to perform thyroid function tests in all depressed patients who do not respond normally to appropriate antidepressor therapy. The precise mechanism of the resistance of depressive symptoms to tricyclic antidepressors is unclear. Several arguments point to an effect of triiodothyronine on central noradrenergic receptors. In practice, significant hypothyroidism implies substitute therapy. Minor thyroid dysfunction (abnormal TRH test alone) may require the association of tricyclic antidepressors and thyroid hormone although the indications and precise dosages of this drug association have not been established.

Antidepressive Agents, Tricyclic↗